<template>
	<div>
		<router-link to='/' tag='div' class="header-abs" v-show='showAbs'>
			<div class='iconfont header-abs-back'>&#xe624;</div>
		</router-link>
		<div class="header-fixed" v-show='!showAbs' :style='opacityStyle'>
			<router-link to='/'>
				<div class='iconfont header-fixed-back'>&#xe624;</div>
			</router-link>
			景点详情
		</div>
	</div>
</template>

<script>
export default {
	name:'DetailHeader',
	data () {
		return {
			showAbs:true,
			opacityStyle:{
				opacity:0
			}
		}
	},
	methods: {
		//获取滚动条距离顶部的距离
		handleScroll () {
			// console.log("scroll")
			const top = document.documentElement.scrollTop
			if(top > 60){
				let opacity = top / 140
				//当opacity>1时，景点详情被隐藏了
				opacity = opacity > 1 ? 1 : opacity
				// console.log(opacity)
				this.opacityStyle = {
					opacity:opacity
				}
				this.showAbs = false
			}else{
				this.showAbs = true
			}
		}
	},
	activated () {
		//监听屏幕滚动条,事件全局绑定，对其他组件有影响
		window.addEventListener('scroll',this.handleScroll)
	},
	deactivated () {
		//全局解绑
		window.removeEventListener('scroll',this.handleScroll)
	}	
}
</script>

<style lang="stylus" scoped>
	@import '~@/assets/styles/varibles.styl'
	.header-abs
		position:absolute
		left:.2rem
		top:.2rem
		width:.8rem
		height:.8rem
		line-height:.8rem
		text-align:center
		border-radius:.4rem
		background:rgba(0,0,0,.8)
		.header-abs-back
			color:#fff
			font-size:.4rem
	.header-fixed
		position:fixed
		// overflow:hidden
		top:0
		left:0
		right:0
		height:$headerHeight
		line-height:$headerHeight
		text-align:center
		color:#fff
		background:$bgColor
		font-size:.32rem
	.header-fixed-back
			position:absolute
			top:0
			left:0
			width:.64rem
			text-align:center
			font-size:.4rem
			color:#fff
</style>